Using oymbiform submerged arc welding; when welding, workpiece is fixed, but portal frame is moved and the speed of moving is controlled by freauency variation; equipping a set of wedlin8 head at each~ groups of guiding post on the beam; using electric dynamo to drive to adjust shirting up and down; using manual adjusting device to adjust shifting left and right; processing meohanictracing the welding line with guiding arc mechanism, wich can get high quality of welding line ; automatically recycling the solder, which can save the labor.